Deep fat fryer unit with solenoid valves and automatic controls

ABSTRACT

A deep fat fryer unit having solenoid operated valves controlled by switches, relays and motor driven timers for controlling the various phases of operation of the unit, including the pumping of oil from a storage tank into a heater tank and then into a cooking pot, through a filter, and return to the heater tank. The oil is continuously circulated through the heater tank and may be circulated through the cooking pot or bypass the cooking pot. A removable crumb conveyor continuously removes crumbs from a crumb well at the lower end of a filter bowl opening into the cooking pot and containing the filter. A vacuum switch is connected with the inlet of the pump and is set to close when the filter is about 50 percent clogged. Closing of the vacuum switch automatically effects return of the oil from the cooking pot to the storage tank and precludes resumption of normal cooking operations until after the filter has been cleaned. Upon removal of the filter and crumb conveyor, a pump-out adapter can be mounted in the filter bowl together with a pump-out hose and the oil pumped out of the crumb-well in response to operation of a sump switch. The storage tank and heater tank can be emptied one at a time by operating separate switches. An emergency STOP switch can be operated at any time to shut down the unit. Automatic signal lights on a control panel indicate when the unit is turned on, when the unit is in operation, when the heating grids are operating, when the heating grids are not working and oil is being circulated through the filter, and when a change of the filter is required.

[451 Oct. 31, 1972 DEEP FAT FRYER UNIT WITH for controlling the various phases of operation of the SOLENOID VALVES AND AUTOMATIC unit, including the pumping of oil from a storage tank O ROL into a heater tank and then into a cooking pot, through a filter, and return to the heater tank; The oil [72] Inventor: Weldon Boggs Tampa is continuously circulated through the heater tank and may be circulated through the cooking pot or bypass panhTampa, 1 the cooking pot. A removable crumb conveyor continuously removes crumbs from a crumb well at the 1971 lower end of a filter bowl opening into the cooking pot [21] APPLNQ; 115,031 and containing the filter. A vacuum switch is connected with the inlet of the pump and is set to close when the filter is about 50 percent clogged. Closing of .99/330, 99/100, 99/ the vacuum switch automatically effects return of the 99/408, 210/167, 210/DlG- 8 oil from the cooking pot to the storage tank and j 37/12 precludes resumption of normal cooking operations .99/330, 336, 403, 40 40 until after the filter has been cleaned. Upon removal 99/406, 407, 408, 342; 2l0/DIG. 8, 167 of the filter and crumb conveyor, a pump-out adapter can be mounted in the filter bowl together with a References Cited pump-out hose and the oil pumped out of the crumbwell in response to operation of a sump switch. The

UNITED STATES PATENTS storage tank and heater tank can be emptied one at a 7/l963 Moore......................,..99/308 time by Operating Separate switches- An emergency STOP switch can be operated at any time to shut United States Patent Boggs [73] Assignee: Food Research & Equipment Com- [22] Filed:

[52] US. Cl.

[51] Int.

[58] Field of Search......

34 Claims, 28 Drawing Figures down the unit. Automatic signal lights on a control panel indicate when the unit is turned on, when the unit is in operation, when the heating grids are operating, when the heating grids are not working and oil is being circulated through the filter, and when a chan of the filter is required.

PATENTED 0m 31 I972 SHEET 02 0F 16 IN VE N 70;? WELDON C. 50655 Yawn/W T RNEYS PATENTED nut 31 1912 SHEET 030F 16 .K 5 5 Z W N fm w .3 g g m3 We SHEET 0'4 [1F 16 INVENTOI? WEL DON C. 50 55 By @QO M HTTORNEYS PATENTEU mm 3 1 I972 PATENTEDucm I972 3.701. 313

sum as 0F 16 4 ON OPE/397E u/w'r STORE H/GH 465 CHANGE 467 //VVENTO/? WELDON C. 504 5 H TTORNE Y5 LOW ope/ware F/Lrr? l/EHT PATENTEI] 0m 3 1 1972 SHEET 08 0F 16 M/VE/YTOR L3 5 WELDON C. 50 65 I I l muv NW PAIENTEDucrsn I972 SHEET U'IUF 16 /NVENTOR wswo/v C. 50665 R/VE Y5 A T TO PATENTEDucm'mn 3.701.313

SHEET 11 0F 16 STORE 356 INVENTOR' Wave/v C 50 5 GYM? PKTENTED B N 7 3,701,313

SHEET 130F 16 EMPTY/N6 STOPQGE T4Nl INVENTOK Wewmv C 605 5 H TTURNE V5 PATENTEuncI 31 m2 SHEET 15 [1F 16 /NVENTOR HTTORNE Y5 NH 4 C mm m N SW v O m a I L 6 55 E 5 5 .MW

DEEP FAT FRYER UNIT WITH SOLENOID VALVES AND AUTOMATIC CONTROLS BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to a deep fat fryer unit for use in lunchrooms, restaurants, hotels, institutions and the like for preparing foods in cooking oil, such as french fried potatoes, onion rings, chicken, scallops, fish, shrimp, etc. Units of the general type involved here are disclosed in Martin U.S. Pat. No. 3,210,193 and Quednau U.S. Pat. No. 3,410,199.

2. Description of the Prior Art Deep fat fryer units, in general, are subject to the problems that frequently arise from the failure of the operators thereof to follow correct procedures in operating the units, and in failing to properly clean and take care of such units.

One common fault with units including a cooking oil filter is that almost invariably, the filter is not cleaned or replaced as often as it should be, with the result that particles of food, crumbs, and/or batter are allowed to remain suspended in the cooking oil for too long a time. This leads to carbonization of the particles with consequent discoloration and breakdown of the cooking oil, thereby greatly shortening its useful life as well as impairing the quality of the food cooked in such oil.

Another problem with prior deep fat fryers, and particularly units including manually operable valves for initiating and effecting various phases of an operating cycle, is that the operators have frequently failed to operate such valves in the proper sequence, with the result that the units have been rendered temporarily inoperable pending corrective action by supervisory personnel.

A further objection to many prior fryer units is that, even though they included a filter for removing crumbs, etc. from the cooking oil, the filters do not remove all matter suspended in the cooking oil, which matter continues to be circulated and to be carbonized, thereby deleteriously affecting the cooking oil.

Still another objection to prior fryer units, and particularly those which include electrical grids for heating the cooking oil in a heating container, is that under certain conditions of operation, the quality of the oil is impaired by remaining in contact with the heating grids for too long a time. This situation can arise when there is only intermittent demand for heated oil in the cooking pot and circulation of the oil through the heating container is curtailed for lengthy intervals. This causes film burning of the oil in contact with the grids and the deposit of carbon on the grids. Thus, the oil is not only damaged, but the heating efficiency of the grids is also reduced.

SUMMARY OF THE INVENTION The present invention overcomes the foregoing difficulties by providing a deep fat fryer unit with automatic controls that are not only simple to operate, but require the operator to perform certain necessary functions that are required to be performed, such as cleaning the filter, and wherein failure to clean the filter will disable the unit so that normal cooking operations cannot be carried on until after the filter has been removed and cleaned.

The present unit also provides a conveyor means for continuously removing crumbs from the cooking oil that were not removed by the filter.

The present unit further overcomes the objection to prior units by providing valve assemblies including solenoid operated valves that are controlled and operated in the proper sequence by manually operable switches, relays and electrically timed control switches, so that any given valve, or pair of valves, required to effect a given function in the cycle of the unit is/or are appropriately actuated.

The further objection to prior units because of film burning of the oil is overcome by the present unit which requires the cooking oil to be continuously circulated through the heater tank, regardless of whether or not any oil is being supplied to the cooking pot.

More specifically, the present deep fat fryer unit includes a cabinet that has a control panel upon which is mounted a master ON-OFF switch and a UNIT ON light to indicate that the unit has been turned on; a HIGH-LOW switch for selecting a cooking pot oil temperature controlled by cooking pot thermostats set to open at about 335F and about 355F, respectively, a HEAT-FILTER switch for supplying current to electrical heating grids in a heater tank and energizing a HEAT signal light to indicate that the heater is in operation; a signal light marked FILTER is energized when the heating elements are not functioning, and which also indicates that oil is circulating through the filter; an OPERATE switch for effecting pumping of oil from the heater tank to the cooking pot and from an oil storage'tank to the heater tank, and for energizing an OPERATE signal light to indicate that the unit is ready for operation; a CHANGE-FILTER signal to indicate that the filter through which the oil is being drawn is partially clogged and requires cleaning; and a STORE switch for effecting the return of oil from the cooking pot to the storage tank.

The fryer unit has a closed circulating system for the cooking oil including the storage tank and heater tank, both of which are completely filled with oil to exclude air (to avoid oxidation) when the unit is out of service. The filter for the cooking oil is mounted in a filter bowl accessible through an opening in the bottom wall of the cooking pot. A continuously running pump and solenoid operated valve assemblies for the storage tank, cooking pot and heating tank, respectively, are connected by tubing to the cooking pot, storage tank and heater tank. Each of the solenoid operated assemblies includes two valves, the operating coils of which are connected in an electrical circuit and controlled by switches, relays and automatic timers to effect filling of the cook pot with cooking oil, circulation of the cooking oil from the heater tank through the cooking pot and filter, or circulation between the heater tank and the pump, etc.

A continuously operating crumb removal conveyor assembly, including an endless belt, extends into a crumb well at the lower end of the filter bowl for removing particles of food, crumbs or batter that have not been removed by the filter. The crumb conveyor is inclined and its lower end extends into the crumb well. The crumb well can be pumped out upon removal of the filter and crumb conveyor by the attachment of a pump-out adapter to the same fitting upon which the filter was mounted. Pumping out of the crumb well is controlled by a separate manual switch mounted upon the door of a control box within the cabinet. The

storage tank and heater tank can be emptied by manually actuating separate switches when the cooking oil is to be changed. These switches are also mounted on the door of the control box. One very important feature of the invention is that the oil that passes through the filter is withdrawn from the filter bowl at a level substantially above the crumb well. This means that there will always be a substantial body of oil in the lower part of the filter bowl and in the crumb well that is not subject to circulation. Therefore, such oil will be relatively cool, compared to the temperature of the oil that is flowing'into the filter bowl and being withdrawn from the filter bowl through the filter element. Consequently, any crumbs or other particles that settle by gravity, or remain suspended for a time in the lower zone of the filter bowl, are not subject to as high a temperature as the oil in the cooking pot. Hence, such particles do not carbonize and detrimenta'lly affect the ,color and taste of the cooking oil. Moreover, such particles eventually settle through the body of cooler oil onto the belt of the conveyor and are promptly removed and discharged into a crumb container at the rear of the unit.

A vacuum switch is connected with the pump inlet and is set to close in response to a given degree of suction resulting from about a 50 percent clogged'condition of the filter. Closing of the vacuum switch results in energizing the CHANGE-FILTER signal light, indicating to the operator that the filter requires cleaning, and effecting the automatic return of the cooking oil to the storage tank if the filter is not cleaned. Should the operator actuate the OPERATE switch to return oil to the cooking pot in an attempt to resume cooking, the suction on the vacuum switch will be temporarily relieved, but will soon be restored due to the partially clogged condition of the filter. The automatic storing cycle will be repeated forcing the operator to clean the filter before normal cooking operations can be resumed.

A heater tank thermostat is set to maintain the oil in the heater tank at a temperature of about 375F to quickly restore any drop in the temperature of the oil in the cooking pot as cold food is introduced into the cooking pot. An overheat thermostat on the heater tank is set to open when the oil temperaturereaches about 395F, to prevent excessive heating of the oil. A STOP switch is provided to enable complete shutting down of the unit at any time.

In accordance with the foregoing, the principal object of the present invention is to provide an automatic, self-contained deep fat fryer unit that is capable of heating, continuously circulating, filtering and otherwise removing crumbs from and storing the cooking oil under conditions least conducive to oxidation and rancidity of the cooking oil and, hence, capable of greatly extending the useful life of the cooking oil.

Another object is to provide a deep fat fryer unit requiring a minimum of effort on the part of the operator and wherein various phases of the cycle of the unit are automatically time-controlled, and others are controlled by the manual operation of separate switches and relays.

Another object is to provide a fryer unit wherein the oil in the cooking pot, the filter bowl and crumb well, the storage tank and the heater tank can be drained therefrom by the manual operation of appropriate switches.

Another object is to provide a fryer unit in which the cooking oil is continuously circulated through the heater tank, and wherein the circulation of the oil is automatically controlled so that it either flows through the cooking pot, or bypasses the cooking pot.

Still another object is to provide means in a fryer unit that is automatically responsive to a given degree of clogging of the filter, for indicating to the operator that a filter change, or cleaning of the filter is required.

A further object is to provide a fryer unit having a filter and automatic means for warning the operator that the filter is becoming excessively clogged, and which will automatically store'the cooking oil in the oil storage tank in the event that the operator fails to change the filter; and which will repeat the warning and storing cycle until the operator changes or replaces the filter, notwithstanding that the operator may attempt to continue operation of the unit and actuate the appropriate switch (OPERATE switch) to return the oil to the cooking pot to resume cooking operations.

A still further object is to provide a fryer unit, wherein duplex solenoid valve assemblies and electrical circuitry are provided to control the flow of the cooking oil for selectively filling the cooking pot, effecting continuous circulation of oil through the heater tank and cooking pot and filter, or bypassing of the oil around the cooking pot and filter, storing the oil, and draining all of the oil from the system.

Still another object is to provide an electrical circuit including timers for timing the cooking pot filling, manually initiated storing and automatically initiated, storing operations.

Still another object is to provide a fryer unit having means, in addition to a filter, for continuously removing crumbs from the cooking oil and discharging the same from the unit.

A still further object is to provide a unitary conveyor for continuously removing crumbs from the cooking oil.

A more specific object is to provide a motor-driven crumb conveyor that can be inserted into and removed from the fryer unit as a complete assembly.

Still another object is to provide a readily removable filter for use in a filter unit and means to prevent crumbs from getting into the cooking oil circulating system during and after removal of the filter.

Another specific object is to provide means for V pumping the cooking oil out of the filter bowl and crumb well after the filter and conveyor have been removed.

Still another object is to provide a fryer unit wherein crumbs that are not removed by the filter pass into a zone in which the cooking oil remains at a much lower temperature than that of the oil in the cooking pot, and from which zone the crumbs are continuously and automatically removed before they canadversely effect the quality of the cooking oil.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a right side elevational view of the deep fat fryer unit.

FIG. 2 is a plan view of the unit drawn to a reduced scale.

FIG. 3 is a perspective view of a skeleton frame for the unit.

FIG. 4 is an inverted fragmentary perspective view of the lower end of the skeleton frame.

FIG. 5 is an enlarged horizontal sectional view through the unit, taken on the line 5-5 of FIG. 1.

FIG. 6 is a fragmentary sectional view, taken on the line 6-6 of FIG. 5, showing the mounting means for the heater tank.

FIG. 7 is a front elevational view of the unit.

FIG. 8 is an enlarged fragmentary vertical sectional view through the filter bowl, taken on the line 8-8 of FIG. 1.

FIG. 9 is an enlarged fragmentary sectional view, taken on the line 9-9 of FIG. 1, particularly illustrating the instrument control panel having legends thereon identifying various switches and signal lights.

FIG. 10 is a fragmentary view of the cover of a control box mounted in the cabinet behind a front main door, showing certain switches mounted thereon.

FIG. 11 is a rear elevational view of the unit.

FIG. 12 is an enlarged transverse, vertical sectional view through the cooking pot, filter bowl and crumb conveyor, taken on the line 12-l2 of FIG. 11.

FIG. 13 is a fragmentary sectional view through the crumb conveyor assembly, taken on the line 13-13 of FIG. 12.

FIG. 14 is a fragmentary sectional view, taken on the line 1414 of FIG. 13.

FIG. 15 is a transverse sectional view through the conveyor and conveyor housing, taken on the line 15- 15 of FIG. 12.

FIG. 16 is a perspective view of a wiper wire for wiping the crumbs off the conveyor belt.

FIG. 17 is an enlarged vertical sectional view through the filter bowl showing a crumb well pump-out adapter mounted upon the fitting that normally supports the filter.

FIG. 18 is a horizontal sectional view, taken on the line 18-18 of FIG. 17.

FIG. 19 is a diagramatic view of the principal components of the unit, showing certain of the valves open and indicating by arrows the direction of flow of the cooking oil during filling of the cooking pot.

FIG. 20 is a view similar to FIG. 19, but illustrating the valves and direction of flow during the cooking phase, with oil circulation through the cooking pot and heater tank, under the control of one of the cooking pot thermostats.

FIG. 21 is a view similar to FIG. 19, but illustrating the valves and direction of flow during bypassing of oil around the cooking pot with continuous circulation through the heater tank when the temperature of the oil in the cooking pot has reached the temperature for which the cooking pot thermostat has been set.

FIG. 22 illustrates the valves and direction of flow during a STORE phase to effect the return of cooking oil from the cooking pot to the storage tank.

FIG. 23 illustrates the filter bowl with the filter bowl cover, filter and crumb conveyor removed and a crumb well pump-out adapter and hose mounted in the filter bowl for pumping cooking oil out of the crumb well.

FIG. 24 illustrates the valves and direction of flow of cooking oil for emptying the storage tank.

FIG. 25 illustrates the valves and direction of flow for emptying the heater tank.

FIG. 26 and 26A comprise a schematic view of the complete electrical control circuit for the unit.

FIG. 27 is a fragmentary view illustrating a modified portion of the circuit for effecting continuous circulation through the cooking pot when the high heat thermostat is controlling the temperature of the oil in the cooking pot.

DESCRIPTION OF THE PREFERRED EMBODIMENT The cooking oil of deep fat fryers is unavoidably contaminated by particles of food, batter, crumbs, etc. that separate from the principal food items that are being cooked. In the interest of brevity, the word crumbs will be used in the following description, and in the claims, with the understanding that it is inclusive of all solid contaminants.

Referring to the drawings, the deep fat fryer unit is generally identified by the letter U and comprises a cabinet K, FIG. 2, made from stainless steel sheet material mounted upon a skeleton frame 16, best shown in FIGS. 3 and 4. The frame 16 is fabricated from sections of angle iron welded together and comprising front uprights 17 and 18, and rear uprights 19 and 20. The front uprights 17 and 18 are connected together at their upper end by a transverse angle iron 22, and at their lower end by a transverse angle iron 24. The rear uprights 19 and 20 are connected together at their lower end by a transverse angle iron 26. The angle irons 17 and 19 at the left side of the frame are connected together at their upper end by an angle iron 28 and at their lower end by an angle iron 30. The angle irons 18 and 20 at the right side of the frame 16 are similarly connected together by angle irons 32 and 34. An intermediate transverse angle iron 36 interconnects the lower angle irons 30 and 34 at a point about midway of the length thereof. A plate 38 is welded to the angle irons 26, 30, 34 and 36, and forms a bottom wall partially closing the lower end of the frame 16, the remainder being open to admit air for cooling purposes.

The lower end of the frame 16 is reinforced at its corners by a triangular gusset plate 40 welded to the angle irons 24 and 30, a gusset plate 42 welded to the angle irons 24 and 34, a gusset plate 44 welded to the angle irons 30 and 26 and a gusset plate 46 welded to the angle irons 26 and 34. A metal pad 48, FIG. 4, is welded to the frame 16 below the gusset plates 40 and 42 and a metal pad 50 is welded to the gusset plates 44 and 46. Rear casters 52, FIG. 1, are mounted upon each of the pads 50. Swivel casters 54 are mounted upon each of the pads 48 at the front of the unit. The casters 52 and 54 render the unit mobile so that it can be readily moved about, as desired.

The front uprights 17 and 18 are concealed behind left and right sections of corner trim 60 and 62, FIGS. 5 and 7 made from stainless steel and tack-welded to the front uprights l7 and 18 on the concealed side thereof. A front panel 64 has inwardly turned side edges 66 that are tack-welded to the adjacent sides of the corner trim 60 and 62. The front panel 64 has an opening 68 providing access to a control panel 70. The control 

1. A deep fat fryer, comprising: a cooking pot having a bottom wall with an opening therein; a filter bowl disposed below said cooking pot and having an upper, open end communicating with said opening; a conduit extending into said filter bowl for withdrawing cooking oil therefrom; an upright, threaded fitting mounted upon said conduit and communicating therewith; and a filter in said filter bowl mounted upon said fitting.
 2. A deep fat fryer as defined in claim 1, wherein a strainer is mounted upon the upper end of the fitting; and wherein the filter includes a hollow core to receive said fitting.
 2. open the fourth and sixth valves to allow oil to continuously circulate through the cooking pot and heater tank;
 3. open the third and sixth valves to allow continuous flow through the heater tank, bypassing the cooking pot;
 3. A deep fat fryer as defined in claim 1, wherein the filter bowl has a chamber located below the conduit for collecting crumbs not removed from the cooking oil by the filter.
 4. A deep fat fryer as defined in claim 3, including means for continuously removing crumbs from the crumb collecting chamber.
 4. open the second and fourth valves to allow oil to be returned from the cooking pot to the storage tank;
 5. open the first valve to drain the storage tank; and
 5. A deep fat fryer as defined in claim 4, in which the crumb removing means comprises a conveyor housing connected to the lower end of the filter bowl, said housing having an opening communicating with the crumb collecting chamber; and wherein a conveyor is disposed in the housing for removing the crumbs from said chamber.
 6. A deep fat fryer as defined in claim 1, including a filter bowl cover overlying the filter and the opening in the bottom wall of the cooking pot, said cover having openings adjacent its outer edge to allow flow of oil from the cooking pot into the filter bowl.
 6. open the fifth valve to drain oil from the heater tank.
 7. A deep fat fryer as defined in claim 6, including baffle means mounted on the underside of the filter bowl cover and arranged to deflect away from the filter any crumbs entrained in the oil that flows from the filter bowl into the cooking pot.
 8. A deep fat fryer as defined in claim 7, wherein the baffle means includes an imperforate conical section above the filter having its upper end disposed inwardly of the openings in the filter bowl cover, and having its lower end extending radially beyond the outer periphery of the filter.
 9. A deep fat fryer as defined in claim 8, wherein the baffle means includes a perforated section extending downwardly from the lower edge of said conical section and surrounding the filter.
 10. A fryer unit comprising, a cooking pot, said cooking pot having a bottom wall with an opening therein; means providing a crumb collecting chamber communicating with said opening; a perforated cover closing said opening; and means extending into said chamber for continuously removing crumbs collected in said chamber to the exterior of said chamber.
 11. A fryer unit as defined in claim 10, in which the means for removing the crumbs from the chamber comprises a conveyor having an endless belt; a discharge chute arranged at the discharge end of said belt; and a crumb collecting receptacle disposed below the discharge end of said chute.
 12. A fryer unit as defined in claim 11, including means at the discharge end of the conveyor for removing crumbs from the conveyor belt.
 13. A fryer unit as defined in claim 12, wherein the means for removing crumbs from the conveyor belt is a wiper wire having a portion extending transversely of the belt.
 14. A fryer unit, comprising: a cooking pot; an oil storage tank having an opening at the lower end thereof; an oil heater tank having an inlet at its lower end and an outlet at its upper end; a pump having an inlet and an outlet; first valve means; tubing connecting said first valve means with the opening of said storage tank and with both the inlet and outlet of said pump; a tube connecting the outlet of said heater tank with said cooking pot for delivering cooking oil thereto; second valve means; tubing connecting said second valve means with said cooking pot, with the tube connecting said heater tank with said cooking pot, and with the inlet of said pump, respectively; third valve means; tubing connecting said third valve means with said tubing connecting said first valve means with said inlet and outlet of said pump, respectively; and with said inlet of said heater tank, all of said valve means normally being closed; and means connected with said three valve means arranged to selectively control said three valve means.
 15. A fryer unit as defined in claim 14, wherein the means for selectively controlling the three valve means is operable to cause opening of said first valve means to establish communication between the storage tank and the inlet of the pump, and to cause opening of the third valve means to establish communication between the outlet of the pump and the inlet of the heater tank to provide for pumping of oil from the storage tank to the heater tank.
 16. A fryer unit as defined in claim 14, wherein, the storage tank and heater tank are of substantially equal capacity, so that when the storage tank and heater tank both are full of oil, the oil in the heater tank will be displaced through the outlet thereof and flow to the cooking pot as oil is pumped from the storage tank into the heater tank.
 17. A fryer unit as defined in claim 14, wherein the means for selectively controling the three valve means is operable to cause opening of the second valve means to establish communication between the cooking pot and the inlet of the pump, and to cause opening of the third valve means to establish communication between the outlet of the pump and the inlet of the heater tank to provide for continuous circulation of oil from the heater tank to the cooking pot.
 18. A fryer unit as defined in claim 17, including an oil filter disposed between the cooking pot and tubing connected to the second valve means.
 19. A fryer unit as defined in claim 14, wherein the means for selectively controlling the three valve means is operable to cause opening of the second valve means to establish communication between the outlet of the heater tank and thE inlet of the pump, and to cause opening of the third valve means to establish communication between the outlet of the pump and the inlet of the heater tank to provide for circulation of oil through the heater tank and the pump and bypassing of the cooking pot.
 20. A fryer unit as defined in claim 14, wherein the means for selectively controlling the three valve means is operable to cause opening of the second valve means to establish communication between the cooking pot and the inlet of the pump, and to cause opening of the first valve means to establish communication between the outlet of the pump and the opening of the storage tank to provide for the return of oil from the cooking pot to the storage tank.
 21. A fryer unit as defined in claim 14, including a drain valve, and branch tubing connecting said drain valve with the tubing connecting the first valve means with the outlet of the pump; and wherein the means for selectively controling the three valve means is operable to cause opening of the first valve means to establish communication between the storage tank and the inlet of the pump, and to provide for pumping of oil from the outlet of the pump through the branch tubing to the discharge valve to effect draining of the storage tank.
 22. A deep fat fryer as defined in claim 14, including a drain valve, and branch tubing connecting said drain valve with the tubing connecting the first valve means with the outlet of the pump, and wherein the means for selectively controlling the three valve means is operable to effect opening of the third valve means to establish communication between the inlet of the heater tank and the inlet of the pump to provide for pumping of the oil from the outlet of the pump through the branch tubing to the discharge valve to effect draining of the heater tank.
 23. A fryer unit as defined in claim 14, including a drain valve, and branch tubing connecting said drain valve with the tubing connecting the first valve means with the outlet of the pump, and wherein the cooking pot has an opening in a bottom wall thereof and a filter bowl is disposed below the cooking pot in communication with said opening, and wherein a crumb well is provided at the lower end of the filter bowl, and wherein the tubing connecting the cooking pot with the second valve means has an inlet fitting located in the filter bowl; and wherein a pump-out adapter is mounted in the filter bowl on said inlet fitting and in communication with said last-mentioned tubing, said pump-out adapter including a pump-out hose extending into the crumb well; and wherein the means for selectively operating the three valve means is operable to cause opening of the second valve means to establish communication between said crumb well and the inlet of the pump to provide for pumping of oil from the outlet of the pump through the branch tubing to the drain valve to effect removal of oil from the crumb well.
 24. A fryer unit as defined in claim 14, wherein the three valve means are solenoid operated valves, and the means for selectively controlling said valves comprises separately operable switches connected in an electrical circuit with said valves.
 25. A fryer unit comprising: a cooking pot; a storage tank; a heater tank having an inlet and an outlet; a pump having an inlet and an outlet; a first valve assembly including a chamber having a first and second independently operable valve therein; a first tube connecting said storage tank with said chamber; a second tube connecting said chamber with the inlet of said pump, all flow through said second tube being controlled by said first valve; a third tube connecting said chamber with the outlet of said pump, all flow through said third tube being controlled by said second valve; a fourth tube connecting the outlet of said heater tank with said cooking pot for delivering cooking oil to said cooking pot; a second valve assembly having a chamber containing a third and a fourth independently operable valve; a fifth tube connecting saId fourth tube with the chamber of said second valve assembly, said third valve controlling all flow through said fifth tube; a sixth tube connecting the cooking pot with said chamber in said second valve assembly, said fourth valve controlling all flow through said sixth tube; a seventh tube connecting the chamber of said second valve assembly with said second tube going to said pump inlet; a third valve assembly having a chamber containing fifth and sixth independently operable valves; an eighth tube connecting the chamber of said third valve assembly with said second tube, all flow through said eighth tube being controlled by said fifth valve; a ninth tube connecting the chamber of said third valve assembly with said third tube, said sixth valve controlling all flow through said ninth tube; a 10th tube connecting the chamber of said third valve assembly with the inlet of said heater tank; and operating means connected with said six valves arranged to selectively effect opening of one, or simultaneous opening of two, of said six valves.
 26. A fryer unit as defined in claim 25, wherein a manually operable drain valve is mounted in a branch tube connected with the third tube; and the operating means for selectively opening the valves is operable to:
 27. A fryer unit as defined in claim 25, wherein a filter bowl is disposed in communication with the cooking pot and has a crumb well in the lower portion thereof; and wherein the sixth tube extends into said filter bowl at a level substantially above the crumb well; and wherein an adapter is connectable with said sixth tube and includes a pump-out hose extensible into the bottom of the crumb well; and wherein the operating means for selectively opening the valves is operable to open the fourth valve to allow oil to be pumped out of the crumb well.
 28. A fryer unit as defined in claim 27, wherein the fourth valve is a solenoid operated valve; and wherein the operating means for the fourth valve comprises a switch connected in a circuit with said fourth valve for effecting opening of said fourth valve.
 29. A fryer unit as defined in claim 25, including a filter in the filter bowl, and wherein a vacuum operated means is connected in the second tube and is responsive to a given suction condition at the inlet of the pump caused by partial clogging of the filter, to effect opening of the second and fourth valves to allow cooking oil to return from the cooking pot to the storage tank.
 30. A fryer unit as defined in claim 29, wherein the vacuum operated means is a NO vacuum switch, and wherein the second and fourth valves are solenoid operated and connected in a circuit with the vacuum switch to open when the vacuum switch is closed.
 31. A fryer unit as defined in claim 25, wherein each of the six valves is solenoid operated; and wherein the operating means connected with the six valves comprises switches connected in a circuit with said valves and selectively operable to effect simultaneous opening of the first and sixth valves, the fourth and sixth valves, the third and sixth valves, the second and fourth valves, and to selectively individually open the first and fifth valves.
 32. A fryer unit, comprising: a cooking pot; a storage tank; a heater tank for heating cooking oil; a pump; a motor connected to drive said pump; a pump relay contrOlling said pump motor; tubing interconnecting said cooking pot, storage tank, heater tank and pump; a pair of NO solenoid operated valves connected in said tubing between said storage tank and said pump; an operate switch; a fill relay; a motor driven timer; a pair of switches operated by said timer; an electrical circuit inter-connecting said OPERATE switch, fill relay, pump relay, solenoid valves, timer motor, pump motor, and timer operated switches, said pump relay having a coil that is energized upon closing of said OPERATE switch and having one pair of NO contacts that close to provide a holding circuit for the pump relay coil and another pair of NO contacts that close to complete a circuit to the pump motor to energize the pump; one of said timer operated switches having NC contacts that complete a circuit to the coil of said fill relay to energize said fill relay, said contacts being opened after a predetermined time interval of operation of the motor to de-energize said fill relay, said fill relay having NO contacts connected with the timer motor to energize said timer motor as said fill relay is energized, said fill relay also having NO contacts that close to complete a holding circuit to said coil of said fill relay, said fill relay having additional NO contacts that close to complete a circuit to said two solenoid operated valves to energize and open said valves to allow flow of cooking oil from said storage tank to said heater tank and cooking pot, said valves being de-energized to close upon de-energizing of said fill relay and opening of the NC contacts of said one timer operated switch at the end of said predetermined time interval.
 33. A fryer unit as defined in claim 32, including a cabinet containing the cooking pot and other components of the unit; and including means communicating with the cooking pot and providing a crumb well; and a motor driven conveyor mounted in said cabinet, arranged to remove crumbs from said crumb well, the motor of said conveyor being connected in the circuit to be energized upon closing of the OPERATE switch.
 34. A fryer unit as defined in claim 33, including a motor driven blower in the cabinet; and an instrument panel mounted on said cabinet having an OPERATE signal light and a UNIT ON signal light mounted thereon; and wherein the blower motor, and said signal lights are energized upon closing of the OPERATE switch. 